FIGS. 1A-2B illustrate a problem to be solved by the device and method(s) disclosed herein. These exemplify fields 130 (e.g., sports fields) where a specific lighting (illuminance L) pattern is desired, e.g., uniform over large areas, and optionally extra brightness such as on bases and pitcher's mound. The “field” may also be a building, billboard, or wall. To illuminate such large areas, many projected light luminaires 200 (commonly referenced as floodlights or spotlights) must be aimed at predetermined portions of the field to produce overlapping light distribution patterns. Multi tier high mast (pole, post) 300 luminaire mounting platforms 302 are typically used, as in the examples shown. Although a lighting pattern on the field (illuminance distribution 132) can be calculated and a beam endpoint 224 determined for where the center line of each luminaire's projected “beam” (beam axis 220) hits the field surface, the actual aiming is very difficult for a variety of reasons (further explained below): The beam endpoint is generally not at the center of the brightest portion of a single luminaire's lighting pattern; the center of the lighting pattern may not be visually obvious, and even the outer boundary of the pattern is difficult to discern because it is typically diffused over a range of lower light levels rather than having sharply defined cutoff edges. Furthermore, each point of the pattern on the field is the sum of all luminaire's overlapping patterns. Thus visual aiming is very inaccurate. Even if computer generated adjustment angle settings are used, due to long distance throws (e.g., 300-500′), difficult-to-measure variations in high mast (e.g., 80-100′) verticality, and lamp output variations from theoretical, even careful adjustment to the calculated elevation and azimuth aiming angles (α, φ) only produces a first approximation that may be off by at least 20 feet.
In the past, lighting uniformity problems due to aiming errors were typically compensated by using an excess of luminaires with very wide beam patterns and redundant overlapping, plus lighting levels high enough to provide adequate light in the darkest areas at the expense of over-lighting other areas. This is very energy-inefficient with much wasted energy. These methods were also supported by the nature of previous large area lighting luminaires. For example, HID light sources in the luminaires, particularly higher output sources, are elongated (e.g., 6 by 1 inch or larger arctube) making it impossible to optically direct a high percentage of the light output into a narrow beam that concentrates light into a relatively small area at long projecting distances. The “spill light”, “up-light”, glare etc. all contribute to wasted energy not being used to provide light where it is wanted.
To address inefficiency, LED lighting luminaires 200 have been developed such as the example illustrated by FIGS. 3A-5B with output specifications such as those shown in FIGS. 6A-7C. Such luminaires achieve high energy efficiency in several ways. First of all, LED light sources 202 are very high efficiency. Importantly, they can be configured as point sources in reflectors that concentrate light in a relatively small field area even at great distances (avoiding wasted spill light, up light, etc.). Their concentrated lighting pattern is quite uniform over a large portion of the beam pattern, and falls off fairly rapidly around the edges. This enables use of fewer luminaires to achieve overall lighting uniformity by essentially tiling the individual beam patterns rather than relying on the redundancy of many overlapping individual patterns with wide fringe areas of gradually decreasing brightness.
The problem now raised is that much more precise aiming of each luminaire is necessary to ensure adequately uniform illuminance on the field. This requires fine tuning of the luminaire aiming angles (α, φ) by a person on the high mast 300.
The current practice for luminaire aiming is to install the luminaires 200 on the pole mounting platform 302 and first adjust to the computer calculated aim settings by rotating the azimuth angle adjustment member 208 to the calculated azimuth angle γ before tightening the luminaire mounting bolt(s), and by rotating the elevation angle adjustment member 210 to the calculated elevation angle α and tightening its locking clamp. Fine tuning to a more precise aim typically takes 2-3 days because the resulting light distribution patterns 132 must be evaluated at night in order to see them, but it is too dangerous for personnel to go up and work on the high mast platform 302 at night. Thus adjustments must be determined at night, then implemented during daylight, however the results cannot be determined until the next night. This is further complicated because moving one luminaire 200 will change the appearance of overlapping areas all around it. This trial and error process is very expensive, and made worse if more precision is desired. If time is cut by settling on approximate aiming, there may be unacceptable non-uniformities (hot spots and dim spots).
Therefor it is an object of this invention to provide a projected light luminaire aiming device and method that overcome the limitations of the prior art to make it faster and easier to achieve optimum illumination patterns by accurate aiming.